Env (gene)

Env is a viral protein that serves to form the viral envelope. The expression of the env gene enables retroviruses to target and attach to specific cell types, and to infiltrate the target cell membrane.

Analysis of the structure and sequence of several different env genes suggests that Env proteins are type 1 fusion machines. Type 1 fusion machines initially bind a receptor on the target cell surface, which triggers a conformational change, allowing for binding of the fusion protein. The fusion peptide inserts itself in the host cell membrane and brings the host cell membrane very close to the viral membrane to facilitate membrane fusion.